Bucuresti bring a 1-0 advantage to Stamford Bridge after their narrow victory in Romania, but despite Chelsea remaining favourites to progress, Lampard has insisted that they must play well to overturn the deficit.
The 34-year-old told the club's official website: "Steaua are a good team. They are technically good on the ball, which most European teams are once you get to this stage of a competition, and it will be a tough game, as simple as that.
"It was a very difficult pitch out there and our pitch will be better.
"The fact we didn't score an away goal is going to make it a difficult night, it will be on a bit of knife edge, but we have to believe we have the character and ability to turn it around."
Lampard will be attempting to score his 200th goal for the club if he is selected on Thursday night.